1. Field of the Invention
The present invention relates generally to microwave ovens and particularly to microwave ovens having an infrared detection element and operative in response to an output from the infrared detection element to provide a heat-cooking operation.
2. Description of the Background Art
Japanese Patent Publication No. 4-68756 discloses a conventional microwave oven employing an infrared detection element to detect a temperature profile on the turntable to detect the position and temperature of a food to be heated that is placed on the turntable.
In such a conventional microwave oven, however, the infrared detection element can only detect the amount of infrared radiation in a limited area (or a field of view), i.e., on the turntable. As such, if such a microwave oven does not have a turntable and a food is placed in the oven""s heating chamber at a location at which a turntable would otherwise be provided, the infrared detection element""s output cannot fully be used to detect the temperature of the food in the heating chamber.
Furthermore, in a conventional microwave oven, with an infrared sensor arranged in a manner, the heating chamber often can have a large number of areas that cannot be covered by the field of view of the infrared detection element. If in such a case a food is placed at a location that the field of view cannot cover, the infrared sensor""s output can also not fully used to detect the condition of the object to be heated.
Furthermore, if juice and the like scattering from a food in the heating chamber adheres to the component of the infrared detection element receiving infrared radiation, it can prevent the infrared detection element from accurately detecting the temperature of the object to be heated. In such a case, the infrared sensor""s output can also not fully be used to detect the condition of the object to be heated.
The present invention has been made to overcome such disadvantages as above and it contemplates a microwave oven employing an infrared sensor having an infrared detection element mounted thereto to ensure that the temperature of an object to be heated is detected to make full use of an output of the infrared sensor to detect the condition of the object to be heated.
The present invention in one aspect provides a microwave oven having a heating chamber accommodating an object to be heated, includes a plurality of infrared detection elements having their respective fields of view in the heating chamber to detect an amount of infrared radiation in the fields of view, the plurality of infrared detection elements being arranged to have the fields of view covering an area in the heating chamber in a first direction from one end to the other end.
In the present invention in one aspect wherever in the heating chamber in the first direction there may exist the object to be heated the infrared detection elements are not required to be moved and their outputs can be used to detect the temperature of the object to be heated.
Thus the infrared detection elements"" outputs can be made full use of to detect the condition of the object to be heated.
The present invention in another aspect provides a microwave oven having a heating chamber accommodating an object to be heated includes: an infrared detection element having a field of view in the heating chamber and attached to the heating chamber in a first direction on one side to detect an amount of infrared radiation in the field of view; and a drive unit driving the infrared detection element to move in a second direction traversing the first direction.
Thus if the infrared detection element is moved its field of view can have an area free of a significant variation in size in the heating chamber.
This can enhance the precision of the temperature of the object to be heated that is derived from an output of the infrared detection element.
The present invention in another aspect provides a microwave oven having a heating chamber accommodating an object to be heated, includes: an infrared detection element having a field of view in the heating chamber and attached to the heating chamber in a first direction on one side to detect an amount of infrared radiation in the field of view; and a drive unit driving the infrared detection element to pivot around an axis corresponding to a line orthogonal to a plane formed by the field of view and extending in one direction closest to one side.
With the drive unit driving the infrared detection element to pivot by a predetermined angle, the heating chamber in the first direction on one side and the other side can have less area that is not covered by the field of view of the infrared detection element. More specifically, the heating chamber can be entirely covered by the field of view of the infrared detection element that pivots by a further reduced angle.
Thus temperature can be detected throughout the heating chamber over a wide area.
The present invention in still another aspect provides a microwave oven having a heating chamber accommodating an object to be heated includes: an infrared detection element having a field of view in the heating chamber to detect an amount of infrared radiation in the field of view; a decision unit determining from an output received from the infrared detection element whether the field of view covers the object to be heated; and a drive unit driving the infrared detection element to move the field of view in the heating chamber, wherein if with the drive unit moving the field of view at a first rate the decision unit determines that in the heating chamber at an area there exists the object to be heated then the drive unit is controlled to move the field of view in the area at a second rate to determine that in the area at a specific subarea there exists the object to be heated, the second rate being lower than the first rate.
Thus in the heating chamber the object to be heated can soon be located.
Thus if the object in the heating chamber is heated for a short period of time its temperature can be detected accurately. That is, if the object in the heating chamber is heated for a short period of time the output of the infrared detection element can be made full use of.
The present invention in another aspect provides a microwave oven having a heating chamber having a wall provided with a window, and accommodating an object to be heated, includes: an infrared detection element provided external to the heating chamber and having a field of view in the heating chamber via the window to detect an amount of infrared radiation in the field of view; a cylinder surrounding the window and extending from the window outwardly of the heating chamber; and a drive unit driving the infrared detection element to move. The cylinder has a specific portion increased in height than a remaining portion of the cylinder. The infrared detection element has a detection window introducing infrared radiation into the infrared detection element. The drive unit drives the infrared detection element to move to allow the detection window to face the specific portion if the infrared detection element is not operated to detect infrared radiation.
Thus the cylinder can be formed by barring a sidewall of the heating chamber and at the specific portion of the cylinder increased in height than the remaining portion of the cylinder the infrared detection element can wait when it is not operated for detection.
As such when it is not operated for detection the infrared detection element can be free from contamination otherwise resulting in an impaired precision in detection. Thus the infrared detection element can provide an output that can more effectively be used to detect the temperature of the object to be heated. Furthermore, readily, without using any additional member and at low cost, and at a location closer to the position of the infrared detection element when it is operated for detection, there can be provided a location for the infrared detection element to wait at when it is not operated for detection.
The present invention in still another aspect provides a microwave oven having a heating unit, a fan provided to cool the heating unit, and a heating chamber having a wall provided with a window, and accommodating an object to be heated, includes: an infrared detection element provided external to the heating chamber and having a field of view in the heating chamber via the window to detect an amount of infrared radiation in the field of view; and a drive unit driving the infrared detection element to move windward of the window as the fan operates.
Thus without using any additional member and at low cost the infrared detection element when it is not operated for detection can be free of contamination otherwise resulting in an impaired precision in detection.
Thus the infrared detection element can provide an output that can more effectively be used to detect the temperature of the object to be heated.
The present invention in a different aspect provides a microwave oven having a chamber with a wall provided with a window, and accommodating an object to be heated, includes a plurality of infrared detection elements provided external to the heating chamber and having a field of view in the heating chamber via the window to detect an amount of infrared radiation in the field of view, the plurality of infrared detection elements having their respective fields of views with their respective centerlines traversing each other in a vicinity of the window.
Thus the heating chamber can have a window minimized in diameter.
This ensures that the infrared detection element can be free of an impaired precision in detection otherwise attributed for example to juice of the object to be heated in the heating chamber that scatters outside the heating chamber. Thus the infrared detection element can provide an output that can more effectively be used to detect the temperature of the object to be heated.
The present invention in a still different aspect provides a microwave oven having a heating unit, a heating chamber with a wall provided with a window, and accommodating an object to be heated, and a plurality of infrared detection elements provided external to the heating chamber and having a field of view in the heating chamber via the window to detect an amount of infrared radiation in the field of view, of the plurality of infrared detection elements a predetermined infrared detection element having a field of view having a portion external to the heating chamber, includes: a decision unit determining whether the object to be heated is covered by the field of view of the predetermined infrared detection element; and a unit stopping a heating operation of the heating unit if the decision unit determines that the object to be heated is covered by the field of view of the predetermined infrared detection element.
Thus in the microwave oven the infrared detection elements includes an infrared detection element having a field of view partially external to the heating chamber and thus incapable of accurately detecting the temperature of the object to be heated and if in the field of view of the infrared detection element there exists the object to be heated the microwave oven stops the current heating operation.
As such, wherever in the heating chamber the object to be heated may be placed, the infrared detection elements"" outputs can be effectively used to control a heating operation, as appropriate.
The present invention in one aspect provides a method of controlling a microwave oven employing an infrared detection element having a field of view corresponding to a respective one of a plurality of areas internal to a heating chamber, to detect a temperature of an object attained in the field of view, including the steps of: calculating for each the area a variation in the temperature introduced within a predetermined temporal period; and referring only to the temperature in the area corresponding to the variation having a largest value and the temperature in the area corresponding to the variation having a value of at least a predetermined percentage relative to the variation having the largest value, to control a heating operation.
Thus of the fields of view of the plurality of infrared detection elements a field of view with a largest variation in temperature within a predetermined temporal period and a field of view with a variation having at least a predetermined percentage relative to the largest variation are extracted as specific fields of view and therein temperature is detected and used to control a heating operation.
Thus the outputs of the plurality of infrared detection elements can be used effectively.
The present in another aspect provides a method of controlling a microwave oven having a heating chamber with an infrared detection element attached thereto in a first direction on one side to detect a temperature of an object in the heating chamber, includes the step of controlling the infrared detection element to detect the temperature of the object in the heating chamber while moving the infrared detection element in a second direction traversing the first direction.
Thus if the infrared detection element is moved its field of view can have an area free of a significant variation in size in the heating chamber.
This can enhance the precision of the temperature of the object to be heated that is derived from an output of the infrared detection element.
The present invention in still another aspect provides a method of controlling a microwave oven having a heating chamber with an infrared detection element attached thereto in one direction on one side and having a field of view to detect a temperature of an object in the heating chamber, includes the step of controlling the infrared detection element to pivot around an axis corresponding to a line orthogonal to a plane formed by the field of view and extending in the first direction closest to one side, to detect the temperature of the object in the heating chamber.
With the drive unit driving the infrared detection element to pivot by a predetermined angle, the heating chamber in the first direction on one side and the other side can have less area that is not covered by the field of view of the infrared detection element. More specifically, the heating chamber can be entirely covered by the field of view of the infrared detection element that pivots by a further reduced angle.
Thus temperature can be detected throughout the heating chamber over a wide area.
The present invention in another aspect provides a method of controlling a microwave oven having a heating chamber with an infrared detection element having a field of view moving to allow the infrared detection element to detect a temperature of an object in the heating chamber, includes the steps of: referring to an output of the infrared detection element with the field of view moving at a first rate to determine that in the heating chamber at an area there exists the object to be heated; and referring to an output of the infrared detection element with the field of view moving in the area at a second rate to determine that in the area at a specific subarea there exists the object to be heated, the second rate being lower than the first rate.
Thus in the heating chamber the object to be heated can soon be located.
Thus if the object in the heating chamber is heated for a short period of time its temperature can be detected accurately. That is, if the object in the heating chamber is heated for a short period of time the output of the infrared detection element can be made full use of.
The present invention in still another aspect provides a method of controlling a microwave oven having a heating unit provided to heat an object to be heated, a fan provided to cool the heating unit, and an infrared detection element having a field of view in the heating chamber via a window provided in a wall of the heating chamber, the infrared detection element having the field of view moving to allow the infrared detection element to detect a temperature of an object in the heating chamber, includes the steps of: determining whether the infrared detection element is being operated to detect temperature; and if the infrared detection element is not being operated to detect temperature, moving the infrared detection element windward of the window as the fan operates.
Thus without using any additional member and at low cost the infrared detection element when it is not operated for detection can be free of contamination otherwise resulting in an impaired precision in detection.
Thus the infrared detection element can provide an output that can more effectively be used to detect the temperature of the object to be heated.
The present invention in a different aspect provides a method of controlling a microwave oven having a heating unit provided to heat an object to be heated and a plurality of infrared detection elements having their respective fields of view in a heating chamber, of the plurality of infrared detection elements a predetermined infrared detection element having a field of view partially external to the heating chamber, includes the steps of: determining whether the object to be heated is covered by the field of view of the predetermined infrared detection element; and stopping a heating operation if the object to be heated is covered by the field of view of the predetermined infrared detection element.
Thus in the microwave oven the infrared detection elements includes an infrared detection element having a field of view partially external to the heating chamber and thus incapable of accurately detecting the temperature of the object to be heated and if in the field of view of the infrared detection element there exists the object to be heated the microwave oven stops the current heating operation.
As such, wherever in the heating chamber the object to be heated may be placed, the infrared detection elements"" outputs can be effectively used to control a heating operation, as appropriate.